The Orlando shooter appears to have taken a page out of ISIS' terrorism playbook

Omar Mateen, the gunman police say entered a gay nightclub in
Orlando early Sunday and killed at least 49 people, called police
and made demands as he was holding several people hostage inside
the club.

The mastermind of November's Paris attacks, Abdelhamid
Abaaoud, instructed Islamic State sympathizers and recruits to
create a hostage standoff during an attack and demand
concessions from police, Rukmini Callimachi,a
foreign correspondent for The New York Times covering Islamic
extremism, noted on Monday morning.

Though there are no signs that 29-year-old Mateen had any
direct ties to ISIS or ever communicated with its members, signs
have emerged that he sympathized with the group — and may have
taken pages from its operational playbook.

"There are several elements of the Orlando siege that
recall operational tactics used in recent months by top ISIS
cadres," Callimachitweeted Monday
morning.

As Callimachi
noted in March, ISIS's instructions to many recruits carrying
out attacks in the West is to "shoot as many civilians as
possible and hold hostages until the security forces" make you a
martyr.

In November, French police spoke to the ISIS-affiliated
attackers inside Paris' Bataclan concert hall
at least five times throughout the night as the militants
were taking hostages and carrying out the massacre that
ultimately left 89 people dead. The attackers apparently
threatened to murder the hostages and throw them out into the
street in front of news cameras if police did not back down. That
was when negotiators ordered police to storm the venue.

Sources told
ABC on Monday morning that the Orlando Police
Departmentdecided to storm the Pulse nightclub
with anarmored vehiclewhen Mateen threatened to begin putting bomb vests on his
hostages. When the police entered, Mateen emerged and began
shooting at the officers. He was then shot and
killed.

In a press conference Monday,
Orlando police said they spoke with Mateen at least three
times over the course of several hours on Sunday morning.
OrlandoPoliceChief John Mina said Mateen appeared
"cool and calm" throughout the attack.

“He really wasn’t asking for a whole lot. We were doing most of
the asking,” Mina said. “Our negotiators were talking with him,
and there were no shots at that time, but there was talk about
bomb vests and explosives. There was an allegiance to the Islamic
State.”

A witness who pretended to be dead in the Pulse nightclub
bathroom and overheard Mateen's phone conversation with police
before they stormed the club said Mateen demanded that the US
"stop killing ISIS." Mateen presumably was referring to the
US-led air campaign against ISIS targets in Syria and
Iraq.

The 911 operator who spoke with Mateen
largely corroborated the witness' statement, paraphrasing
Mateen as saying: “I’m doing this to protest the US bombing in
Syria and Iraq and the killing of women and children … I’m doing
this in solidarity with the
Tsarnaev brothersand Moner Abusalha.”

The Tsarnaev brothers were al-Qaida-inspired extremists who
bombed the Boston Marathon in 2013. Abusalha was an
American suicide bomber who traveled to Syria to carry out an
attack in the name of al-Qaida affiliate Jabhat al-Nusra.
Mateen's mention of two al-Qaida-inspired terrorists indicates
that he may been sympathetic to radical Islamists broadly, not
just ISIS.

"These are the identical demands that the Paris bombers
made when they called police from inside the Bataclan: End the
strikes in Syria," Callimachi tweeted.

She continued: "Assuming Orlando is at least
ISIS-inspired there are only 2 other incidents I know of where an
IS shooter took hostages/made these demands: One is
Bataclan on 11/13. Other was (and I need 2double check this)
Amedy Coulibaly's hostage standoff at a Kosher supermarket in
January 2015."

Amedy Coulibaly in a video
he made proclaiming his allegiance to ISIS.Screen grab

Other elements of the nightclub massacre align with ISIS
"procedure" for such attacks, Callimachi noted.

"Other thing ISIS has codified is procedure
through which adherents claim attacks in their name. Rule is
shooter needs to pledge allegiance," she said. Mateen called 911
sometime Saturday night andpledgedallegiance to ISIS, mentioning the Boston Marathon bombers
during the call.

"You have to be pretty deep in ISIS' ideology to understand
the importance of pledging bay'ah (allegiance) & how it must
precede attack," Callimachi noted.

Other experts have pushed back against that notion,
claiming that pledging allegiance to an extremist group before
carrying out a terror attack is a "code" of conduct that doesn't
require a sophisticated knowledge of ISIS ideology.

"That 'code' is available for all, splayed across internet
— no secret," Maria Abi-Habib, a Middle East reporter for The
Wall Street Journal, tweeted
Monday. "Doesn't mean they have sophisticated knowledge of
ISIS."

She added: The "success of ISIS is that it's like
McDonald's of Jihad — made it accessible to all."

This
undated combination of photos provided by the FBI, left, and the
California Department of Motor Vehicles shows San Bernardino
shooters Tashfeen Malik, left, and Syed
Farook.AP

Whether Mateen studied ISIS' ideology or simply read about
its methods in Western newspapers remains unclear.

Mateen's pledge of allegiance to ISIS and his request
that the US "stop killing" its members does not necessarily mean
he was in direct contact with the radical jihadists, or
thatthe groupdirected him to carry
out the attack. President Barack Obama said on Monday that there
was no clear evidence Mateen was directed by ISIS or part of a
larger ISIS plot.

But Mateen's ties to radical Islam
apparently go back to 2013, when he was first investigated by
the FBI for making threats to coworkers and hinting at possible
ties to terrorist activities. He was investigated again in 2014
for his possible ties to Abusalha, the American suicide
bomber, who was also from Florida.

The FBI interviewed Mateen and determined that his contact
with Abusalha was minimal and did not constitute a
substantive threat at the time.

"At this point, it's anyone's guess as to how involved Omar
Mateen was with either al-Qaida or ISIS," Chris Harmer, an
analyst at the Institute for the Study of War,
told Business Insider on Sunday.

As many analysts have noted,Tashfeen
Malik — a shooter in the San Bernardino attack that left 14
people dead — also pledged allegiance to ISIS leader Abu Bakr
al-Baghdadi. But she had no known direct ties to the extremist
group.

"The 911 call pledging allegiance to ISIS shows [Mateen]
was emotionally or intellectually sympathetic to ISIS, but does
not show that he had any contact with ISIS," Harmer said. "Bottom
line: It is clear that Mateen was, at a minimum, influenced by
ISIS, expressed some loyalty to ISIS, but it is not clear that he
had any communication or connection with ISIS beyond
that."